Basic concepts Flashcards
What is a Rigid Boundary?
Prevents a system from changing shape or size
What does Adiabatic mean?
Prevents a system from changing unless the boundary is changed
What is an Isolating System?
Both adiabatic and rigid
What is a Diathermal system?
Permits flow-through of heat
What is a permeable system?
Permits passage of matter, otherwise impermeable
What is a closed system?
Mass cannot cross the boundaries but energy can
What are the 3 types of property of a system?
Intensive Extensive Specific
Intensive property
System size independent
Cannot be added up
Examples: Temperature and Pressure
Extensive property
System size dependent
Can be added up
Examples: Volume and mass
Specific property
Extensive properties/unit mass
Specific Volume
Volume/unit mass
The inverse of density V=v/m=1/density
Specific Gravity
The ratio of the density of a substance to the density of some standard substance (usually water at 4 degrees C)
What is a State?
At a given state all values for the properties are known, changing one property changes the state
What is Equilibrium ?
A system is said to be in equilibrium if it maintains thermal, mechanical, phase (the mass of the phases) and chemical equilibrium
What is the State Postulate?
The thermodynamic state of a simple compressible system is completely specified by 2 independent intensive properties
What is a Quasi-equilibrium or quasi-static process?
A process where the system remains practically in equilibrium at all times
Isobaric
Constant Pressure
Isothermal
Constant Temperature
Isochoric
Constant Volume
Isoentropic
Constant Entropy
What is a cycle?
A process (or series of connected processes) with identical end states
Carnot Cycle
- Isothermal Expansion
- Adiabatic Expansion
- Isothermal Compression
- Adiabatic Compression
Diesel Cycle
- Intake
- Compression
- Power
- Exhaust
What is Heat?
The energy transfer that appears at the boundary when a system changes its state due to a difference in temp. between the system and its surroundings
What is Work?
The energy transfer that appears at the boundary when a system changes its state due to movement of a part or the whole of the boundary under the action of a force
What is the ice point?
A mixture of ice and water that is in equilibrium with air saturated with vapour of 1 ATM. Pressure
What is the steam point?
A mixture of liquid water and vapour (with no air) in equilibrium at 1 ATM. pressure
